Postprandial blood glucose
The daily management of diabetes mellitus is a complex interaction between blood glucose measuring, lifestyle aspects and drug therapy. Large epidemiological trials such as UKPDS (United Kingdom Diabetes Prospective Study) have shown that an optimal blood glucose adjustment has beneficial long-term effects on type-2 diabetics’ risk of micro- and macrovascular secondary complications.
But, while in the past glycated haemoglobin (HbA1c) combined with fasting plasma glucose were considered the most important target values to achieve optimal glycaemic control, newer insights have shown that postprandial blood glucose (PBG) plays an equally – if not greater – role in diabetes therapy.
In 2007, the International Diabetes Federation (IDF) launched the ‘Guideline for Management of Post meal Glucose’, which emphasises that diabetics should have their blood glucose levels closely monitored after meals in order to optimise diabetes control and reduce the risk of complications, particularly cardiovascular disease.
However, the huge importance of PBG for the decrease of micro- and macrovascular complications in diabetes is still underestimated, said Antonio Ceriello MD, Head of the Research Department on ‘Diabetes and Cardiovascular Disease’ at the Insititut d'Investigacions Biomèdiques, August Pi i Sunyer (IDIBAPS), in Barcelona, and Chairman of the IDF Post meal Glucose Guideline Committee, during an interview with Daniela Zimmermann (EH).
Focusing on the importance of PBG, Dr Ceriello made two specific points: ‘First, postprandial glucose might be an independent risk factor for cardiovascular disease, even in patients suffering from impaired glucose tolerance also known as pre-diabetes. This assumption is still controversially discussed because, while there are many epidemiological studies supporting this concept, by now the results of intervention trials are still controversial. Secondly, it is clinically proved that reducing postprandial hyperglycaemia helps to achieve the optimal HbA1c target value (7%). Moreover, a growing number of studies suggest that to reduce post-meal plasma glucose excursions contributes to the reduction of ‘glucose variability’, an emerging risk factor for diabetic complications and the worst prognosis in the critical care setting.
PBG guidelines must change
‘Our current IDF recommendation says that two-hour post-meal plasma glucose should not exceed 7.8 mmol/l (140 mg/dl) – as long as hypoglycaemia is avoided – which is the normal glucose tolerance in non-diabetics. However, it is now recognised that the blood glucose peak is between 1 and 1 ½ hours, so we will have to narrow the time frame down in future guidelines.
Post-meal glucose and cardiovascular diseases
‘Insulin is a peptide hormone of vital importance, but too much of a good thing can lead to overkill, which is often true for type-2 diabetics having a decreased sensitivity to insulin action and producing too much insulin that can’t be exploited by the body. Furthermore, type-2 diabetics suffer an insulin resistance. Consequently, when a diabetic eats, the glucose stays in the blood plasma, where it causes great damage. The condition of high glucose concentration in the blood induces high releases of free radicals (oxidative stress), which are an important trigger for cardiovascular disease. These arteriosclerotic vessel damages, and inflammations caused by free radicals, increase the risk for severe circulation disturbance. Therefore, diabetes is the reason for thousands of myocardial infarctions and strokes, as well as foot ulcers, amputations, blindness and nephropathies.
Hospital staff awareness
‘We have to differentiate between the intensive care unit (ICU) and other wards. The ICU staff is well educated to monitor metabolic and other parameters continuously and they are also trained to react quickly in a critical situation. But, as soon as a patient is moved from ICU to another department the staff’s diabetes knowledge decreases. So awareness of glucose variability and hyperglycaemia definitely must be improved -- because normalising glycaemia can enormously improve prognosis for patients, in every medical field.
‘PBG is, of course, part of this strategy. In 2009, the American Diabetes Association (ADA), in conjunction with the American Heart Association (AHA), published guidelines concerning Diabetes Care in the Hospital to optimise diabetic control in a clinical environment.’
Postprandial hyperglycaemia avoidance
‘Besides physical exercise, healthy nutrition with a low glycaemic load, and pharmacological treatment with drugs that lower PBG, self monitoring blood glucose (SMBG) is the most important strategy for successful diabetes management. SMBG gives a direct feedback to the diabetic and the doctor who takes care of him and is therefore the key element to adjust therapy if necessary.
‘Today, SMBG is fortunately simplified by modern meters and electronic diabetes management programmes. Another important tool is the digital diabetes logbook to evaluate data over a longer period of time or compare the influence of different external factors on the metabolism in real-time.
‘Diabetes is a chronic disease that demands a great deal of self-responsibility from the patient and a continuous control from the physician. But a keen metabolic control pays off.
15.07.2010
